(1) Field of the Invention
This invention generally relates to the art of antisubmarine warfare training and is a device for simulating a submarine mast positioned above a water surface.
(2) Description of the Prior Art
A submarine mast (e.g., periscope or snorkel) extending above the water surface can be detected by several methods. In a first example of detection, metallic components of the submarine mast will display a radar footprint. In a second example of detection, the submarine's forward speed will cause the mast to generate a visible wake which is generally much easier to see than the mast itself. In a third example of detection, the thermal plume associated with diesel exhaust from a snorkel can be seen using infrared cameras. Lastly, a sniffer-type chemical sensor can discern various compounds contained within the diesel exhaust. All of these techniques for detection are presently used by aircraft and surface ships to conduct antisubmarine warfare (ASW) operations.
The use of naval service or real submarines to train ASW crews is problematic, limited by high expense and risk as well as the low priority of such training relative to a submarine's other missions. As such, low-cost, low-risk methods of training personnel to detect submarines are needed.
One method of detection assistance is to tow a catamaran behind an unmanned underwater vehicle (UUV). The catamaran would have a radar reflector and/or a heat source to mimic submarine characteristics. The catamaran approach lacks realism in that it does not permit the simulator to pop out of the water unannounced and disappear minutes later, as a real submarine mast would behave. Also, a catamaran's wake and visual appearance are quite different from those of a submarine mast. Finally, the catamaran must be released by the UUV and recovered separately in order for the UUV to perform other tasks during its run.
Another method of detection assistance is to deploy a periscope-like mast from a UUV traveling just below the surface. One working prototype extends 26.5 feet in length and weighs 3600 pounds. Bow planes increase the width of the UUV to 67 inches. Furthermore, the capability of the prototype is limited to periscope simulation. However, like all large UUVs, the prototype is expensive to build and operate. It requires a specially trained support crew, a complete logistics system and extensive maintenance, and its size makes the prototype cumbersome to launch, recover and transport. As a result, there is needed a low-cost mast simulator that can be towed and which resembles and operates like the mast of a real submarine.
The following references disclose ASW training devices, but do not disclose a mast simulator with the following characteristics: a visual appearance close to that of a submarine periscope or snorkel protruding above the water surface; a radar footprint equal to that of a submarine periscope or snorkel protruding above the water surface; a wake approximating that generated by a submarine periscope or snorkel protruding above the water surface; an infrared signature similar to that of a snorkeling diesel-electric submarine; chemical vapor emissions similar to those of a snorkeling diesel-electric submarine; programmable, submarine-like speed and maneuvering characteristics; an ability to surface/deploy and retract/submerge the mast simulator multiple times during a single run; the minimum drag exerted by the mast simulator when it is not surfaced/deployed; mast simulator hardware which can be jettisoned by the UUV when no longer needed during a mission; low production and maintenance costs; and relatively easy to handle, launch and recover.
Mason (U.S. Pat. No. 5,144,587) discloses an expendable moving echo radiator suitable for providing a decoy to attract a homing torpedo and divert the torpedo away from its intended target. The reference further discloses an expandable and collapsible curtain for deployment from a capsule launched from a submarine or other sea vessel. In its expanded configuration, the curtain is characterized by a physical profile sufficient to reflect acoustic waves aid to generate echoes substantially similar to echo signals generated by an actual, full-size submarine or other target. The cited reference further discloses propulsion means, as well as means for capturing a torpedo's sensors. As such, the expendable device can be used to simulate a submarine for ASW training. In using the echo radiator as a target, the expendable device can be preprogrammed or remotely controlled for self-navigation purposes.
Haisfield et al. (U.S. Pat. No. 5,247,894) discloses a decoy which simulates the evasive tactics of a submarine under attack for pulse echo-type search systems and which can be ejected through the flare tube of a submarine.
Chace, Jr. et al. (U.S. Pat. No. 5,490,473) discloses an expendable underwater vehicle for use in training naval forces in ASW which is between three and five feet in length and about five inches in diameter. The cited reference further discloses an in-water variable speed feature, a variable tonal levels feature, an autonomous evasion feature, and a high-power integrated pinger feature.
It should be understood that the present invention would in fact enhance the functionality of the above references by providing a submarine mast simulator having all of the visual, radar, thermal, chemical and wake generation characteristics of a real submarine mast yet is reusable and reliable.